A rescuer moves supplies, including food and water, into a helicopter before a mission in Beijing on Aug 3, 2023. (WANG ZHUANGFEI / CHINA DAILY)

The National Meteorological Center has declared the recent heavy rainfall in the Beijing-Tianjin-Hebei region from Saturday to Tuesday "a historically extreme event".

The intensity of the rainfall surpassed previous significant rainstorms in the region, including those in 1996, 2012 and 2016.

During the four days, rainfall pummeled Beijing for 83 hours, the center said.

The extreme heavy rainfall in the Beijing-Tianjin-Hebei region can be attributed to typhoons and the mountainous landscape in the region, said Zhang Hengde, deputy director of the National Meteorological Center

Over three days, 26 national weather monitoring stations reported accumulated rainfall exceeding historical records.

The extreme heavy rainfall in the Beijing-Tianjin-Hebei region can be attributed to typhoons and the mountainous landscape in the region, said Zhang Hengde, deputy director of the center.

An abundant supply of water vapor in the atmosphere was brought by the remnants of Typhoon Doksuri and combined with the southeastern airflow of a subtropical high and moisture transported from distant Typhoon Khanun, said Zhang.

"The vapor had been converging toward the North China Plain. Plus, the presence of mountain ranges such as the Taihang and Yanshan mountains caused an uplifting motion, forcing the water vapor to condense and intensifying the rain," he said.

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According to meteorological statistics, the accumulated rainfall during this period was double or even triple the historical average for the same period.

Villagers being evacuated from a flooded area on Aug 2, 2023 pass through a landslide on Nanyan Road at the junction of Changping and Mentougou districts in Beijing. (PAN ZHIWANG / FOR CHINA DAILY)

The greatest impact was seen in Beijing, Tianjin, and central parts of Hebei.

The cumulative rainfall in Hebei province's Liangjiazhuang village in Xingtai surpassed 1,003 millimeters within two days, which is more than twice the amount of precipitation the city typically receives in a whole year

The cumulative rainfall in Hebei province's Liangjiazhuang village in Xingtai surpassed 1,003 millimeters within two days, which is more than twice the amount of precipitation the city typically receives in a whole year.

Similarly, some parts of Beijing recorded more than 700 mm of accumulated rainfall, far exceeding the previous records.

Such extreme heavy rainfall can lead to urban flooding and waterlogged areas, greatly affecting transportation, urban operations, agricultural production and people's daily lives, the center said.

On Friday, the center renewed a blue alert as Typhoon Khanun, the sixth typhoon this year, is moving northeast on the East China Sea.

From 2 pm Friday to 2 pm Saturday, strong winds with speeds of 39 to 74 kilometers per hour are expected in most parts of the South China Sea, the Beibu Gulf, the Taiwan Strait, the Bashi Channel, areas to the east of China's Taiwan island, the East China Sea and the waters near the Diaoyu Island as well as the coastal areas of Zhejiang, Fujian, Taiwan island, Guangxi, Leizhou Peninsula of Guangdong and Hainan, with wind gusts surpassing 100 kilometers per hour, according to the center.

Typhoon Khanun is expected to move out of the East China Sea on Sunday morning, the center said, as it is forecast to weaken as it moves toward southeastern Japan.

It has advised the aforementioned regions to make emergency preparations for the typhoon.

READ MORE: Khanun: China activates level-IV emergency response

Over the next 10 days, another typhoon is expected in the northwest Pacific and the South China Sea, but it is unlikely to affect China, the center said.

China has a four-tier, color-coded weather warning system, with red representing the most severe warning, followed by orange, yellow and blue.